McDonald’s announced Sunday that Quarter Pounders will be back on the menus of hundreds of restaurants after tests showed beef patties were not the source of an E. coli poisoning outbreak linked to the popular burgers.

In a statement from McDonald’s, it was stated that the US Food and Drug Administration continues to believe that chopped onions from a single supplier are a possible source of contamination. He said the Quarter Pounder (without the slivered onions) will continue to be sold at affected restaurants next week.

The epidemic started as of Friday expanded to at least 75 people Federal health officials said there were patients in 13 states. A total of 22 people were hospitalized, and two developed a dangerous complication of kidney disease, the Centers for Disease Control and Prevention said. One person died in Colorado.

McDonald’s shares took a 7% hit when news of the outbreak broke last week. RJ Hottovy, head of analytics research at Pacer.ai, says there has been a 6-9% year-over-year decline in foot traffic in the last few days.

But he added: “They acted quickly by taking Quarter Pounders off the menu. I think that was a smart move. They were saying it had nothing to do with beef. And I think it was all smart. It will definitely have an impact, but some of that will be mitigated.”

RELATED | Onion supplier issues recall following E. coli outbreak at McDonald’s

Initial information analyzed by the FDA showed that uncooked sliced ​​onions used in the burgers were a “possible source of contamination.” McDonald’s confirmed that Taylor Farms, a California-based produce company, was the supplier of the scallions used at restaurants involved in the outbreak and that they came from a facility in Colorado Springs, Colorado.

When the outbreak was announced Tuesday, McDonald’s removed its Quarter Pounder burger from menus in several states, mostly in the Midwest and Mountain states. McDonald’s said Friday that slivers of onions from its Colorado Springs facility were distributed to about 900 of its restaurants, including some at transportation hubs such as airports.

The company said it removed sliver onions from that facility from its supply chain on Tuesday. McDonald’s said it has decided to “indefinitely” stop supplying onions from Taylor Farms’ Colorado Springs facility.

McDonald’s said the 900 McDonald’s restaurants that normally buy slivered onions from Taylor Farms’ Colorado Springs facility will continue selling Quarter Pounders without slivered onions.

McDonald’s stated that the source of the outbreak was not beef patties in tests conducted by the Colorado Department of Agriculture.

The Department of Agriculture received large quantities of fresh and frozen beef patties collected from several Colorado McDonald’s locations connected to the E. coli investigation. All samples were found negative for E. coli, the ministry said.

RELATED STORY | McDonald’s announced that Chicken Big Mac will be sold in the USA. Here’s when you can get it

Taylor Farms said Friday that it is preemptively recalling yellow onions shipped to customers from its Colorado facility and continues to work with the CDC and FDA during the investigation.

While it remains unclear whether the recalled onions were the source of the outbreak, some other fast food restaurants, including Taco Bell, Pizza Hut, KFC and Burger King, removed the onions from some menus in certain regions this week.

Colorado was the state with the highest number of cases reported, with 26 cases as of Friday. At least 13 in Montana, 11 in Nebraska, five each in New Mexico and Utah, four in Missouri and Wyoming, two in Michigan, and one each in Iowa, Kansas, Oregon, Wisconsin and Washington, the CDC reported. got sick.

McDonald’s said in a statement Friday that it was not withdrawing the Quarter Pounder from any additional restaurants and noted that some cases in states outside the original region were linked to travel.

The CDC said some people who got sick reported traveling to other states before their symptoms began. At least three people said they ate at McDonald’s during their travels. The illnesses were reported between September 27 and October 11.

The outbreak involves infections with E. coli 0157:H7, a type of bacteria that produces a dangerous toxin. It causes about 74,000 infections annually in the United States, leading to more than 2,000 hospitalizations and 61 deaths each year, according to the CDC.

Symptoms of E. coli poisoning can appear rapidly within a day or two after consuming contaminated food. These usually include fever, vomiting, diarrhea or bloody diarrhea, and signs of dehydration (little or no urination, increased thirst, and dizziness). The infection is especially dangerous for children under 5 years of age, the elderly, pregnant women, or people with weakened immune systems.